CSS sprites are great for minimizing the number of requests made for loading images, however, the design and coding part can be painful if there are too many images.

Spritemapper is a tool for easing this process by merging multiple images into a single one and creating the CSS positioning rules for each slice.

The tool is a simple command-line tool that performs the job via a Python package including its own PNG and CSS parser (without any 3rd-party dependencies).

jQuery has lots of plugins and jQuery UI to improve its functionality in many ways.

Ninja UI is a plugin for the framework that brings new alternatives to them in a single package.

It includes widgets like buttons, accordion, icons, tooltips/modal box, slider, rating, tabs, auto-suggest and canvas-powered loader icon.

They are unobtrusive and the icons used actually come as a separate plugin that is in the form of web fonts.

P.S. Its documentation is not complete yet but the source of the examples are pretty self-explanatory.

Skeleton is a set of CSS and JS files which aims to create a solid starting point when developing websites.

It has a 960px grid which adapts itself into any width/device including mobile and tablet browsers.

The boilerplate is not a UI framework and only contains the most basic styles for forms, typography and buttons.

Skeleton has jQuery built-in for only creating tabs, so it is easily possible to use it without any (or with other) JS frameworks.

We all know robots.txt, the text file that is uploaded to the root folder of websites and helps us communicate with the search engine bots for telling them which pages to not to index.

What if we want to communicate with humans and tell them who built the website? There is usually not a suitable space for this in websites and visitors may not be interested in seeing such an information inside "about" pages (in most cases).

This is where Humans.txt, which is an initiative for knowing the people behind a website, comes in.

Just like robots.txt, you upload a humans.txt file to the root folder of the website and can mention every detail that "careful eyes" would be interested in learning about the team behind, the designers, developers, copywriters, etc.

It won't be wrong to expect it getting popular as some big guys like Google or Flickr already have it. And, WRD has it too : ).

Active Admin is a Ruby on Rails plugin for creating functional and good-looking back-end (administration) interfaces.

The interface is designed to be easy-to-use for non-technical users and flexible for developers.

By default, the plugin installs Devise, a widely-used authentication solution for Rails, in order to handle system users.

It can display data in different views (like grid, table, block or blog)  that can be paginated or filtered and every data displayed can be exported as XML, JSON or CVS.

Forms can be created and customized very quickly, thanks to the nice DSL created by Formtastic.

And, it is possible to design every page in many ways like using multiple grids, sidebar sections and more.

BundleHunt, the bundle of quality design apps and resources, is now presenting its 4th bundle which is only available for the next 2 weeks.

It includes 13 Mac OS X apps and design resources for a price of $49.99 (rather than $780). Every item in the bundle is very handy and designers/developers will easily make use of them.

• Snippets: a powerful Mac OS X app that for storing your code pieces.
• ColorSchemer Studio 2: a pro color-matching application for Mac OS X & WIN OS.
• Layers: an outstanding screen capture app for Mac OS X. Layers captures every Item as a PSD layered image.
• ShoveBox: a Mac OS X app that catches all those little scraps of information that you can't act on now but would rather not forget.
• WPBundle is offering 3 WordPress themes, built on top of the WooThemes Framework, of your choice.
• SmashingMagazine's newest 3 e-books in their store: Mastering Photoshop for Web Design, Volume 2, Professional Web Design Vol. 2 and Getting the Hang of Web Typography. The 3 e-books are available as PDF, ePUB, Mobipocket.
• Symbolicons: a family of 465 royalty-free vector icons and symbols for most any use.
• Decompose: a Mac OS X app allowing an easy extraction of elements from pictures to use them to make composite images.
• Tapptics: a collection of design files & step-by-step training created to help designers, developers & anyone to save time and money creating mobile apps.
• Picons's all 440 icons: Basic 1 and 2 are brand new icons that contain 440 hand-crafted vector items, built on a grid and sharing the same visual language.
• ThemeFuse: 3 WordPress themes of your choice with Standard license.
• WeGraphics: 30 of their high quality design element sets such as vector art, textures, fonts and brushes.
• IconJar: 211 hand crafted icons for UI designers.

The 4th BundleHunt is only available until the end of May 2011 and every purchase comes with a chance of winning an iPad2.

Perkins is a HTML5/CSS-powered framework for building websites quicker and easier.

It comes with a simple template which includes most of the supported tags and a set of LESS stylesheets + mixins for popular items like navigation, rounded corners, gradients and more.

All of the items (typography, forms, tables, buttons, etc.) are styled very nicely and there is a @font-face icon set included for instant-inline icons.

Tooltipsy is a jQuery plugin that provides a flexible base for creating tooltips.

Compared to other plugins, it comes with minimum default styles or animations but gives you the complete control over them.

It can be positioned however you wish, look and feel can be totally customized with CSS and any type of animations can be implemented.

There are also few settings like "the ability to aligning the tooltip according to the cursor or the element" and "its distance from them".

Tooltipsy is very well-documented and a set of samples show the flexibility offered.

Bookmarklets are amazing little helpers whether you are a web designer/developer or a standard internet user. There is a handy one for everybody.

For ex, lately, I am regularly using Holmes.css as a part of my HTML debugging process, Syntaclet on dev-related articles and Readability for reading long articles.

And, there are many other useful bookmarklets out there (check out 15 Must-Have Bookmarklets For Web Designers And Developers).

Boo.kmarked is a very simple and free to use web application that converts any given JavaScript into a bookmarklet.

The application just adds the <a> tag with a function that calls your script accordingly and that's all.

P.S. There are also other alternatives like Bookmarkleter or Bookmarklet maker.

CodeIgniter is a powerful framework for creating PHP web apps much faster. Bonfire, a solid base for the framework, makes the process even speedier.

It is a set of tools (like a ready-to-use user management system, e-mail queue, database backup), all built inside an elegant and customizable UI.

The codebase is completely modular and built around HMVC (Hierarchical-Model-View-Controller pattern).

Bonfire has a flexible template/theme system which is capable of WordPress-like parent/child themes.

Also, it comes with several other handy features like extending the CodeIgniter profiler.